I would go with a local supplier willing to give you "Right Hand Column" prices on the metal
"SpeedyMetals" or "OnLineMetals" are WAY Overpriced and will dash any hopes you ever had of being competitively priced of any local job shops. I do however believe "OnLineMetals" does include a certificate of Alloy analyst which may be useful on occasion - but by no means offsets the need to consistently be paying premium plus.
Also the scrap bin at some metal suppliers is going to be useful as I found a good source for "Sub-Plates" in a bin of rejected 14"x20"x2" cuts of 6061 Al. At $3 a pound they ran $22 each but when performing 2nd ops or a combination of 1st and 2nd Ops they are invaluable.
You can see the subplate on the left hand side of the table here.
I think I was checking my backlash in that photo and uploaded to 1 of the groups I belong to checking to see if I was doing it right.
In a combination 1st and 2nd Op program the vise would be where the indicator is now for the 1st Op. The program would immediately go to the 2nd Op using a "Fixture Offset" cutting down on my "Reload" time
But if I have a run of 10 or more of any given item, I am going to want to use a size of metal stock that produces the least amount of waste. That's is where a good metal supplier is going to save you money in the long run.
Or just try and get "SpeedyMetals" to deliver you a 4'x8'x3" sheet of AR plate